a) Field of the Invention
This invention relates to a fob detector for use in the supply line between a pressurized beverage container and a dispensing means,particularly for beers.
b) Description of the Related Art
One of the problems encountered when dispensing draught beers, and especially draught stout, occurs when the pressurized container from which the beer is to be dispensed is nearly empty and there is a build up of the fob or froth which constitutes a considerable wastage. Several pints of fob must be cleared from the dispensing system before the next full beer container can be connected to the system. It is known to use a fob detector in the beer line between the container and the dispensing point--see British Patent Specification No. 1,357,953 of Porter-Lancastrian Limited. Irish Patent Specification No. 47813 of the present inventor (the contents of which are incorporated herein by reference) describes apparatus for use in inhibiting dispense of fob comprising a chamber having an inlet aperture for receiving liquid beverage under pressure from a supply source, and an outlet aperture for discharging such liquid beverage to a dispensing means, the outlet aperture being surrounded by a seating, a float movable within the chamber relative to the seating, the float being buoyant in the liquid beverage but not in fob and being arranged to make sealing engagement with the seating when the chamber is empty or substantially empty of liquid beverage, and means to displace the float from the seating. The chamber is provided with a vent communicable with the top of the chamber and closable by a valve unit which is in screw-threaded engagement with the chamber top component. The vent valve is normally kept closed. However upon connection of the device to a fresh supply source, the vent valve is opened manually to release pressure from inside the chamber.
The vent valve as described in Irish Patent Specification No. 47813 is screw-threaded. It has a head inside the chamber which seals against the seating of a valve port. However when the valve has been opened by rotating the knob, it must be closed again after use by counter-rotation of the knob. This gives rise to a serious risk that the valve may be left open by an operator who is handling the changeover of beer kegs, particularly in an urgent situation when beer is in demand. If the valve is left open, part or even all of the contents of the new beer keg may be lost through the vent port and may go to waste.
It has been proposed to use a spring loaded vent valve in which a valve head is lifted upwardly off a valve seat by a cam lever. However this type of valve actuation also gives rise to a risk of the valve being left open.